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Equations in a twodimensional, laterally averaged estuaryriver model previously developed using boundaryfitted (curvilinear) coordinates were compared to those in traditional onedimensional river models. Unlike the latter ones, the equations expressed in the curvilinear coordinates account for the effect of curvilinear geometries of a meandering river and describe stratifications in the water column and densityflow intrusions in estuaries. Equations for traditional onedimensional river models are, in fact, special cases of the equations employed in the present model.

This study investigated the effect of mid-pregnancy shearing (at Day 70 of pregnancy, P70) on herbage intake of grazing single- and twin-bearing ewes, lamb birth weight, and cold resistance of new-born lambs. At pregnancy diagnosis on P50, 30 single-bearing and 30 twin-bearing ewes were allocated either to be shorn at P70 (n = 15 for each pregnancy rank) or to remain unshorn to serve as controls (n = 15 for each pregnancy rank). All ewes were mated over a 3-day period with synchronisation of their oestrus. Herbage intake was measured indirectly from in vitro pasture digestibility and faecal output of grazing ewes, with the use of intra-ruminal chromium slow-release capsules, over six 5-day periods from P64 to P105. The weights of placental and fetal tissues were assessed in a subgroup of 16 ewes at P140 and P141. In the remaining sheep, lamb liveweight at birth and during lactation until weaning at 103 days of age was measured, and cold-resistance of new-born lambs was assessed by measuring summit metabolic rate (SMR) by indirect calorimetry. Ewe liveweight (corrected for fleece weight), condition score, and herbage intake during pregnancy were not affected by shearing treatment. Mid-pregnancy shearing did not affect placental weight, but increased the relative weights (i.e. g/kg liveweight) of fetal thyroid gland and lungs and reduced the relative weight of adrenal glands and heart. The ratio of secondary to primary wool follicles in near-term fetal skin was about 10% higher in offspring of shorn than of unshorn ewes. The metabolic rate of fetal hepatic tissue was increased by mid-pregnancy shearing, particularly in twin fetuses, possibly indicative of an increase in placental transport of nutrients to the fetuses. This conclusion is supported by the greater birth weight (average response 0.5 kg) of lambs born to ewes shorn at mid-pregnancy. Mid-pregnancy shearing also increased the SMR of new-born twin lambs by 16%, but decreased the SMR of singleton lambs by 26%. These results indicate that mid-pregnancy shearing can increase lamb birth weight without increasing ewe herbage intake or placental weight. An increase in the efficiency of nutrient uptake by the placenta is implied, and possible effects on the activity of thermogenic tissues are discussed.

Pregnancy shearing has been shown to increase lamb birthweights. However, results have been variable between studies. It has been suggested that the birthweight response to pregnancy shearing is greatest in conditions in which the unshorn dam gives birth to lambs of low birthweight. This study was designed to examine the birthweight response under 2 differing maternal treatments (one designed to restrict fetal growth and the other designed not to limit fetal growth), with the aim of explaining the variation observed in pregnancy shearing studies. Mixed aged Romney cross ewes were either shorn during mid pregnancy (n = 55) or left unshorn (n = 50). At shearing, ewes were split into either a ‘maintenance’ group (64 kg at shearing and fed to permit total ewe liveweight gain equivalent to expected conceptus growth during mid- to late-pregnancy) (n = 52) or a ‘low’ group (54 kg at shearing and fed to permit total ewe liveweight to increase at half the expected conceptus growth during mid- to late-pregnancy) (n = 53), respectively. Mid-pregnancy shearing was found to increase the birthweights of singletons (5.6 v. 4.9 kg, P < 0.05) but not twins, and of lambs born to maintenance group ewes (by 0.6 kg, P < 0.05), but not low group ewes. Additionally, mid-pregnancy shearing had no effect on the thermoregulatory capacity of twin-born lambs. When the results of this study are considered with those of previous New Zealand pregnancy shearing studies, they suggest that there are 2 criteria (and not one, as previously suggested) that must be met to achieve a response to pregnancy shearing. Firstly, the dam must have the potential to respond [i.e. have been destined to give birth to an otherwise lightweight lamb(s)], and secondly, the ewe must have the means to respond (i.e. an adequate level of maternal reserves and/or level of nutrition to partition towards additional fetal growth). thermoregulatory capability, survival.

This study was designed to determine whether dam nutrition during mid to late pregnancy influences birthweight responses from pregnancy shearing. Romney-cross ewes were either shorn during mid pregnancy (n = 68) or left unshorn (n = 66). Ewes were offered either a maintenance level of feed (a level of nutrition that enabled the dam to maintain conceptus-free liveweight) or a high level of feed (a level of nutrition that enabled the dam to gain 100 g/day of conceptus-free liveweight in addition to expected fetal growth) during the mid pregnancy (post-shearing) period (from Day 70 of pregnancy (P70) until P101). At the end of this period ewes were offered either maintenance or a high level of nutrition during late pregnancy (P102–P140). Pregnancy shearing was found to increase lamb birthweight (average birthweight 5.4 0.1 v. 5.1 0.1 kg) without differentially affecting the birthweight of singles or twins. Dam feeding level post-shearing did not affect the birthweight response to mid pregnancy shearing. Pregnancy shearing treatment had no effect on the summit metabolic rate of twin lambs. However, when results of this study are compiled with those of previous mid to late pregnancy shearing studies under similar conditions, it appears that the birth weight response from pregnancy shearing is greatest where lightweight lambs are born to unshorn (control) ewes. summit metabolism, thermoregulatory capacity, lamb survival.

The effects of season of growth and monensin treatment on ruminal digestion of fresh-cut autumn and spring pasture were measured in a single group of ruminally fistulated castrated male sheep, housed indoors in metabolism crates. Responses were assessed in terms of ruminal volatile fatty acid molar proportions, ammonia concentration, pH, apparent digestibility of the pasture, and nitrogen balance of the animals. Blood plasma concentrations of insulin, glucose, beta-hydroxybutyrate, urea, and NEFA were also evaluated. Autumn pasture contained significantly lower proportions of water-soluble carbohydrate (P< 0.05), cellulose (P< 0.05), and lignin (P< 0.05) and increased pectin (P< 0.05), hemicellulose (P< 0.05), and crude protein (P< 0.10) concentrations when compared with spring pasture. Voluntary DMI by sheep of autumn pasture was lower (P< 0.01) than that of spring pasture and was significantly (P< 0.05) reduced by monensin treatment. Monensin treatment significantly decreased the ruminal molar proportions of acetic acid (P< 0.10) and butyric acid (P< 0.001) and increased the molar proportions of propionic acid (P< 0.001) and minor VFA (P< 0.01). Nitrogen retention of the sheep was significantly (P< 0.05) reduced by monensin treatment. Plasma glucose levels were increased (P< 0.10) by monensin treatment during the fourth 5-d collection period in both seasons. Chemical analysis suggested that the composition of autumn pasture was different from that of spring pasture and that this was manifested in vivo by increased DMI and digestibility of spring vs autumn pasture. Ruminal fermentation of autumn pasture also had an increased acetate-to-propionate ratio compared with spring pasture. Monensin treatment acted consistently across seasons by increasing the proportion of propionate and decreasing the proportion of acetate in ruminal fluid.

Sulfur amino acid supplementation increases wool production in sheep at low planes of nutrition but it is unclear whether there is any benefit of supplementation at planes of nutrition above maintenance and what implications this might have for wool quality characteristics. This experiment directly investigated the interaction between sulfur supplementation and plane of nutrition in terms of wool growth and fibre characteristics. Twenty-four Romney ewes, acclimatised in individual metabolism units over a 7-week pre-treatment period, were allocated to 1 of 4 treatment groups based on a 22 factorial arrangement. Groups were low (L) or high (H) intake (0.8 or 1.3 maintenance, respectively) with continuous intravenous infusion of either saline (–Cys) or cysteine (+Cys, 2 g/day). During the 3-month treatment period, measurements were obtained for liveweight, plasma cysteine concentration, wool sulfur concentration and output, clean wool growth, mean fibre diameter (MFD), length growth rate (LGR), colour, loose wool bulk, handle, and crimp frequency and character. Clean wool growth response (P &lt; 0.05) to cysteine supplementation was greater for the L sheep (6.06 v. 4.31 g/100 cm2) than the H sheep (7.20 v. 6.13 g/100 cm2). The response to supplementation in LGR (P &lt; 0.01) was similar in both H (14%) and L (20%) sheep. There was no response in MFD due to sulfur supplementation, although fibre diameter measurements made along the fibres suggest that there was a response in L but not H sheep (P &lt; 0.1). Wool sulfur concentration and output increased as a result of cysteine supplementation but concentration increased more in L (30.6 v. 24.5 mg S/g; P &lt; 0.01) than in H sheep (28.4 v. 26.2 mg S/g). Qualitative electrophoresis analyses suggested that the increase in wool sulfur was achieved primarily by an increase in ultra-high-sulfur proteins. Crimp frequency and character were both significantly (P &lt; 0.01) enhanced by cysteine supplementation. It is concluded that cysteine supplementation, at feed intakes that commonly occur in the commercial situation, can produce a useful increase in wool growth. This growth increase is primarily accomplished by increasing length growth rate rather than fibre diameter, which should also improve the value of the wool fibre produced. wool quality, wool sulfur, wool protein.

Muscle growth, myofibre number, type and morphometry were studied in large hindlimb muscles of single and twin fetal lambs during mid to late gestation. Placental insufficiency, evident by lower total placentome weight and number per fetus, resulted in reduced fetal weights from 100 to 140 days gestation in twins compared with singletons (at 140 days: 5016 108 g v. 5750 246 g, respectively; P&lt;0.05). However, competition between littermates did not consistently reduce muscle mass (15–22%) until 140 days gestation. Apparent myofibre number increased with age, indicating that the full complement of myofibres in some large hindlimb muscles may be achieved during early postnatal life. Litter size did not impact on apparent myofibre number in the semitendinosus, plantaris or gastrocnemius muscles. However, a transient effect on myofibre number in the adductor femoris muscle was observed from 80–120 days gestation. The phenotypic maturation of myofibres was unaffected by increasing litter size. Smaller muscle mass in twins was associated with smaller myofibre cross-sectional area in the semitendinosus, adductor femoris and gastrocnemius muscles at 140 days gestation. A similar trend was observed for the plantaris muscle. These results indicate that while competition between littermates for nutrients in late gestation can impact on both fetal and muscle mass, the fetus has the capacity to buffer against the effects of restricted nutrient supply on myofibre hyperplasia and phenotypic maturation, but myofibre hypertrophy is compromised. Extra keywords: development, myofibre hypertrophy, ontogeny, sheep.

Cellular development of the adductor femoris muscle from twin and single fetuses was studied at 140 days gestation to evaluate the effect of moderate fetal growth retardation on myofibre development. Twin fetuses had lower bodyweights (13%) and disproportionately small adductor femoris muscle weights (22%) compared with single fetuses. Reduced muscle mass was associated with smaller myofibre cross-sectional areas (CSA) and lower DNA content (22%), indicative of fewer myonuclei and retarded myofibre hypertrophy. Myofibre number and the phenotypic maturation of the myofibres were similar between twins and singletons. These results indicate that even modest growth restriction during fetal life can negatively influence myofibre hypertrophy, highlighting the importance of fetal nutrition for muscle growth. Large muscles, such as the adductor femoris, have intrafascicularly terminating myofibres, which necessitates accurate sampling of the muscle when investigating possible perturbations in morphological characteristics (e.g. between singletons and twins). The second objective of the present study was to investigate the impact of the sampling site on the morphological parameters of the adductor femoris muscle. The apparent total myofibre number decreased from the proximal to the distal region of the adductor femoris muscle. The apparent number of slow-twitch fibres also decreased from the proximal to the medial region, but was not different between the medial and distal regions of the muscle. Similarly, myofibre CSA differed between the medial and distal regions. These results indicate that, particularly with large muscles, such as the adductor femoris, which has intrafascicularly terminating myofibres, single site sampling for the determination of morphological fibre characteristics may generate misleading results and that careful selection of the sampling area may be necessary. Extra keywords: fetus, morphometry, sheep.

Discusses the Scottish Festival in Quechee, Vt. sponsored by the St. Andrews Society of Vermont and Scotland-by-the-Yard, which is held to celebrate Scottish heritage. INSET: A calendar of Highland Games and Scottish Festivals..

AbstractRams from the Massey University fleeceweight-selected (FW) and control (C) lines of Romney sheep (13 per line) were slaughtered at 16 months of age to determine responses in body composition to 35 years of single trait selection for greasy fleeceweight. FW rams were heavier than C rams and, at a common liveweight, had heavier hearts, livers, thymus glands, and adrenal glands but a lower reticulo-rumen weight. Carcasses of FW rams were heavier and longer than those of C rams but there was no difference between the lines in dressing-out percentage. At a common carcass weight, FW and C rams had a similar content of water, protein, and fat in the carcass. Subcutaneous fat depths and soft tissue depth GR were generally lower in FW rams and there was a redistribution of tissue in the carcasses of these rams compared with C rams such that hind leg weight was increased at the expense of the shoulder, loin, and rack. Hind legs of the FW rams had higher weights of dissectible muscle and bone, lower weights of dissectible fat, a heavier and longer femur, and lower muscularity (depth of muscle relative to length of an adjacent bone) at a common carcass weight than those of C rams. It is concluded that responses in body composition to selection for greasy fleece-weight are small but generally favourable, except for the decrease in muscularity.

Equations in a two‐dimensional, laterally averaged estuary‐river model previously developed using boundary‐fitted (curvilinear) coordinates were compared to those in traditional one‐dimensional river models. Unlike the latter ones, the equations expressed in the curvilinear coordinates account for the effect of curvilinear geometries of a meandering river and describe stratifications in the water column and density‐flow intrusions in estuaries. Equations for traditional one‐dimensional river models are, in fact, special cases of the equations employed in the present model.

AbstractA study was conducted to determine whether the measurement of blood metabolite levels in fasted 110-day pregnant ewes could provide a more accurate identification of those requiring nutritional supplementation in late pregnancy than that provided by identification of pregnancy status (single versus multiple) alone. Border Leicester x Romney ewes (195), aged 2–8 years and pregnant to one of two synchronised matings, were studied. At 110 (range 108–112) days of gestation they were weighed and blood-sampled by jugular venipuncture after a 24-h fast. Blood plasma was analysed for concentrations of glucose, non-esterified fatty acids (NEFA), β-hydroxybutyrate, urea, and creatinine. Ewes were set-stocked immediately before lambing and sex, birthrank, and birthweight of their lambs recorded. Two-year-old ewes had significantly lower plasma concentrations of glucose and creatinine, and higher concentrations of β-hydroxybutyrate, than older ewes. Ewes mated in Cycle 2 had lower concentrations of glucose, urea, and creatinine but higher concentrations of β-hydroxybutyrate than ewes conceiving to the second cycle, probably because they were removed from pastures with low residual herbage masses before fasting. Ewes carrying multiple pregnancies (twin or triplet), as measured by number of lambs born, had reduced concentrations of glucose but elevated βhydroxybutyrate and NEFA concentrations, relative to those carrying singles. Plasma glucose, NEFA, and β-hydroxybutyrate concentrations were significantly related to total weight of lamb born, but they did not significantly improve the 63% of variation in this trait explained by pregnancy status. Maternal plasma urea and creatinine concentrations were not related to total weight of lamb born to each ewe. It is concluded that, in ewes of medium fecundity, measurement of blood metabolites at 110 days of pregnancy does not enhance the accuracy with which those requiring additional nutrition in late pregnancy can be identified, compared with identification on the basis of pregnancy status alone.

The purpose of this study was to examine whether the performance of pre-lamb shorn sheep is influenced by pasture allowance in the immediate post-shearing period and whether the relationship between performance and pasture allowance differs according to whether the ewes are shorn by standard comb or cover comb. The trial was replicated across two years to allow for climatic variations between years. Fifty-four ewes were used in each year in a 3 × 3 × 2 factorial design with three shearing treatments (standard comb, cover comb, and unshorn), three sward surface height (SSH) treatments (nominal 3, 5, and 7 cm), and two pregnancy status treatments (single and twin). Rectal temperatures of standard comb or cover comb ewes were significantly lower (P < 0.05) than those of unshorn ewes on day 2 following shearing (S2), and on S4, S8, and S20. Pasture allowance, however, did not affect rectal temperatures of shorn ewes. There was an interaction (P < 0.05) between shearing treatment and SSH. Thus, liveweight gains during the period from pregnancy day 115 (P115) to P135 were 275, 613, and 4518 g; 1557, 2314, and 3997 g; and 3623, 2894, and 3997 g for standard comb, cover comb, and unshorn (control) ewes set-stocked on 3, 5, and 7 cm SSH, respectively. There was no interaction between shearing treatment and SSH for lamb birth weight, but the birth weights of lambs born to standard comb ewes (4.9 ± 0.1 kg) were significantly greater (P < 0.05) than those of lambs born to unshorn ewes (4.3 ±0.1 kg). There were no effects of shearing treatment or SSH on lamb weaning weight, ewe wool growth rate or mean fibre diameter. Likewise, there were no effects of shearing treatment or SSH on ewe organic matter intake (OMI), except on the second day following shearing when the OMIs of ewes set-stocked on 3 cm (941 ± 147 g) were significantly (P < 0.05) lower than those of ewes grazing 5 cm (1628 ±101 g) or 7 cm (1349 ± 135 g) SSH pasture. The results suggest that hypothermia, as determined by rectal temperatures and induced by pre-lamb shearing, cannot be avoided by pasture management, provided SSH exceeds 3 cm. This reflects the fact that, in the period immediately after shearing, ewes do not increase feed intake when provided with increased pasture allowances.

The cover comb is a discrete, relatively simple technology which generates financial advantages to farmers by reducing sheep losses, particularly for late winter-spring shearings, and possibly by conserving pasture when feed reserves are low. The development, research evaluation, and extension of the cover comb have been reasonably well documented, and this enabled a spreadsheet cost-benefit model to be constructed to evaluate the return on investment in research, development, and extension associated with the cover comb. The model developed for the analysis comprised components for research and extension costs, the change in use of the cover comb by sheep class and region through time, and the benefits that accrued from alternative on-farm applications of the cover comb. Sensitivity analyses were conducted for increases of 9.5% and 12.9% of all adult sheep in New Zealand being shorn by cover comb between 1989 and 2000, reductions in sheep losses of 0.5% and 1%, and discount rates of 5% and 10%. The internal rates of return ranged from 485% to 1330%, and the net present values from $12.30 million to $49.22 million. The cover comb succeeded because it is a simple, easily adopted, risk-reducing technology that is applicable to a large animal population. This case study illustrates that investment in on-farm research can be highly profitable.

Treatment with 2a-bromoergocriptine mesylate (CB154) was used to determine the effects on ovine lactogenesis of short- versus long-term suppression of circulating prolactin (PRL) concentrations in single- and twin-bearing ewes and whether the effects were associated with changes in plasma concentrations of progesterone or insulin. Ewes were housed under constant photoperiod (18 h light: 6 h dark) from 3-4 weeks pre-partum until 8 days post-partum, then grazed outdoors. Ewes were treated daily with subcutaneous injections of 2 mg CB154 for 20 ± 1. days pre-partum (CB20 group, n = 10), or for 9 ± 1 days pre-partum (CB9 group, n = 10), or with excipient injections for 19 ± 2 days pre-partum (Control group, n = 9), and milked daily for the first week, then on Days 14, 21, and 28 post-partum. CB154 inhibited PRL secretion and delayed lactogenesis with no consistent effects on plasma progesterone or insulin concentrations. PRL concentrations were higher (P < 0.05) in CB9 than in CB20 ewes from 14 days pre-partum until 1 day post-partum and plasma PRL concentrations in the two groups converged as they approached parturition (P < 0.01). There was no significant treatment group by pregnancy rank interaction for circulating PRL concentrations. Although the delay in lactogenesis did not differ between CB20 and CB9 ewes, CB 154 treatment was more effective in reducing milk yield in twin-bearing than in single-bearing ewes when used for 20 days, but not for 9 days, pre-partum (P < 0.05). These results indicate that, during the period 20-10 days pre-partum, CB154 treatment had a marked effect on milk yield in twin- but not single-bearing ewes which can not be explained by corresponding effects on plasma PRL, progesterone, or insulin concentrations.

Rumensin® (monensin sodium) and Compudose® (oestradiol-176) can both promote liveweight gain of pasture-fed cattle. Limited information exists about their effects on carcass and meat quality characteristics or their combined effects on beef cattle performance. This study examined the effects of Rumensin (R) and Compudose (C), alone and in combination, on the growth, carcass characteristics, and meat quality of steers finished at pasture. Seventy-two yearling steers (290 ± 4 kg) received either no treatment, R, C, or R+C for the 266-day experimental period. C led to increased liveweight gain (P < 0.001) but R had no effect and the R x C interaction was not significant. Weight-corrected height was lower (P < 0.05) in Compudose-treated cattle. R had no significant effect on any carcass or meat quality traits and no interactions with C were found. Compudose treatment increased carcass weight (P < 0.001) and dressing-out percentage (P < 0.05), and decreased kidney + pelvic fat weight (P < 0.005) and side length (P < 0.01). Compudose decreased M. longissimus ultimate pH (P < 0.001) and increased meat brightness L* (P < 0.05), but Warner-Bratzler peak shear values were higher (P < 0.05) in meat of the C group. It is concluded that R has little effect on growth, or carcass or meat characteristics of steers at pasture, and that it has no influence on the way C affects these characteristics.

Carcass and meat quality traits of Hereford × Friesian once-bred ("calved") heifers (n = 15) were compared with those of bred but not pregnant ("empty") heifers (n = 10) and “unbred” heifers (n = 10). Unbred and empty heifers had similar carcass weights (mean = 242 kg), but the mean carcass weight of the calved heifers was 31 kg less (P < 0.001) even though they were 6 months older. Weight-adjusted dressing-out percentages were lower (P < 0.05) in calved heifers than in unbred heifers, with values for the empty group being intermediate. Calved heifers had longer carcasses and femur bones than unbred (P < 0.05) and empty (P < 0.001) heifers at the same carcass weight. Hind-quarter cut yields were highest for the calved group. Measures of fatness adjusted for carcass weight were generally lower for the calved group, but differences were seldom significant. Meat quality was assessed on samples of Longissimus dorsi collected before chilling at c. 90 min post-mortem and kept above 12°C for 24 h. Beef of calved heifers was significantly brighter (i.e. higher reflectance values, P < 0.05) than meat from unbred heifers, with the empty group having intermediate values. Overall, Warner-Bratzler shear force parameters as measures of meat tenderness were similar for meat from unbred, empty, and calved heifers. It is concluded that, relative to unbred heifers, the quality of meat and carcasses of heifers that have raised one calf on pasture to c. 5 months of age will be similar, although at the same carcass weight, skeletal dimensions will be greater and dressing-out percentages slightly lower. Thus the attractive features of once-bred heifer production from the point of view of efficiency are unlikely to be offset by changes in carcass or meat quality. In a second experiment, meat quality characteristics were compared for samples of Longissimus dorsi from the carcasses of 28 once-bred heifers either before (as for Experiment 1) or after chilling. Some significant differences existed between the pre- and post-chill samples but the correlations obtained were generally moderate to high indicating that taking samples before chilling, in addition to avoiding variation in cold-shortening, also gave quality results similar to those obtained under commercial conditions.

Beef-breeding cows are traditionally weaned at about 7-8 months of calf age in New Zealand but early weaning may have advantages in once-bred heifer beef production systems. This study compared the growth performance, and carcass and meat quality characteristics, of 31 once-bred Hereford × Friesian heifers mated to Angus (17 heifers) or Charolais (14 heifers) sires from which calves were removed at either 12 weeks (Day 84 of lactation = L84) or 21 weeks (Day 147 of lactation = L147) of lactation. These are referred to as the “W84” (calves weaned at Day 84 and their dams) or “W147” (calves weaned at Day 147 and their dams) groups respectively. During L84-L147, W84 heifers had higher daily liveweight gain (LWG) than the W147 heifers (0.79 versus 0.51, PSE = 0.07 kg/day, P < 0.01). Calves weaned at L84 had significantly lower daily LWG than W147 calves during the period L84-L147 (0.73 versus 1.30, PSE = 0.05 kg/day, P < 0.001). This resulted in 30 kg lower (P < 0.001) liveweight in W84 versus W147 calves at the time of weaning for the latter group. During the period L137-L147, the W84 versus W147 heifers had herbage organic matter intakes (estimated using intraruminal chromium controlled-release capsules) of 3.01 versus 3.50 (PSE = 0.16) kg DM/100 kg LW per day (P < 0.05). Heifers whose calves were removed at L147 spent more time grazing (P < 0.01) and ruminating (P < 0.10), and less time idling (P < 0.01) than the W84 heifers. Overall, weaning time did not significantly affect the carcass and meat quality characteristics of W84 or W147 heifers. Results are discussed in the context of weaning time effects on the productivity and carcass and meat quality traits of once-bred heifers.

The development of hepatic somatotrophic receptors and plasma concentrations of insulin-like growth factor-I (IGF-I) were investigated at five different ages (2, 20, 35, 105 and 165 days) in four male pigs per group. The specific binding of 125I-labelled porcine GH (pGH) to hepatic somatotrophic membranes was very low at 2 days of age (0·53±0·12%), and increased progressively (P<0·01) with advancing age to 3·60 ± 0·95% at 165 days of age. Specific binding of 125I-labelled bovine GH (bGH) to the same membrane preparations was markedly higher than binding of 125I-labelled pGH; it also showed a distinct developmental increase (P<0·01) with age from 4·4 ± 0·55% at 2 days of age to 24·0±1·90% at 165 days of age. Plasma concentrations of IGF-I increased significantly (P<0·01) from 79 ± 14·0 μg/l at 2 days of age to 610 ± 64·0 μg/l at 165 days of age.Non-linear regression analysis of the competitive binding data using bGH as labelled and unlabelled ligands showed linear Scatchard plots in the three youngest age groups, with an association constant (Ka) of approximately 3·5 litres/nmol. Curvilinear Scatchard plots were observed in the two oldest age groups. The Kafor the higher affinity binding site (approximately 5·0 litres/nmol) was very similar to that for the sole site observed in the younger animals. The Kaof the lower affinity binding site was approximately 0·35 litres/nmol. There was a significant (P<0·01) developmental increase in the capacity of the higher affinity binding site from 12 ± 4·6 pmol/100 mg liver at 2 days of age to 91 ± 23·0 pmol/100 mg liver at 165 days of age.These studies demonstrate heterogeneity of somatotrophic hepatic membranes in the pig and show that low concentrations of a high affinity binding site are already present in newborn pigs. A considerable developmental increase was observed in the capacity of this binding site which correlated significantly (r= 0·82, P<0·01, n= 20) with plasma concentrations of IGF-I. The role of the lower affinity binding site which was observed in addition to the high affinity binding site in older pigs is less clear. The data from the present study support the hypothesis that the postnatal rise in plasma concentrations of IGF-I is associated with the developmental increase of the capacity of the high affinity somatotrophic receptors.Journal of Endocrinology(1989) 123,25–31

A study was conducted to investigate developmental patterns of plasma concentrations of insulin-like growth factor-I (IGF-I), body growth and body composition in mice from lines selected for seven generations on the basis of low (L) or high (H) plasma IGF-I, and in a random-bred control (C) line. Litter size was standardized to eight individuals with equal sex ratios (as far as possible) within 48 h of birth. Pups were weaned at an average of 21 days and separated on the basis of sex. Blood samples were collected from one male and one female of each litter on days, 21, 42, 63 and 105 for analysis of plasma concentrations of IGF-I. The animals were then killed and analysed for water, fat and crude protein content.The plasma concentration of IGF-I was influenced by line (P<0·05) but not by sex. Significant (P< 0·001) differences in liveweight between mice from L and H lines were first evident at 21 days of age. From 28 until 105 days of age the H line was significantly (P< 0·001) heavier than both L and C lines, but differences between C and L lines were inconsistent and mostly non-significant. The growth velocity of the H line was significantly greater than that of C or L lines between 14 and 42 days of age, but differences in growth velocities of C compared with L lines were generally non-significant.Nose–anus length was significantly (P<0·01) affected by sex and line from 42 to 105 days of age, but anus–tail length was not affected by sex or line at any age. Effects of sex and line on empty (digesta-free) body weight and wet weights of carcass and skin plus viscera fractions followed a pattern similar to those of liveweights. The effects of sex and line on protein, water and fat content also paralleled their effects on body size. Differences between males and females, and between the lines, in amount of protein, water and fat could be entirely accounted for by the corresponding differences in body weight.It is concluded from these results that divergent selection on the basis of plasma IGF-I at 42 days of age resulted in lines of animals differing in plasma IGF-I from 21 days of age until maturity. These divergent concentrations of IGF-I are associated with differences between the lines in body growth, particularly during the period of accelerated growth at puberty, but not with changes in body composition.Journal of Endocrinology(1990) 124,151–158

Summary.In castrated rams (Romney and Poll Dorset, n= 8 for each breed), inhibition by testosterone treatment (administered via Silastic capsules) of luteinizing hormone (LH) pulse frequency, basal and mean LH concentrations, mean folliclestimulating hormone (FSH) concentration, and the peak and total LH responses to exogenous gonadotrophin-releasing hormone (GnRH) were significantly (P< 0·01) greater during the nonbreeding than during the breeding season. Poll Dorset rams were less sensitive to testosterone treatment than Romney rams. In rams not receiving testosterone treatment, LH pulse frequency was significantly (P< 0·05) lower during the nonbreeding season than during the breeding season in the Romneys (15·8 ± 0·9 versus 12·0 ± 0·4 pulses in 8 h), but not in the Poll Dorsets (13·6 ± 1·2 versus 12·8 ± 0·8 pulses in 8 h). It is concluded that, in rams, season influences gonadotrophin secretion through a steroid-independent effect (directly on hypothalamic GnRH secretion) and a steroid-dependent effect (indirectly on the sensitivity of the hypothalamo–pituitary axis to the negative feedback of testosterone). The magnitude of these effects appears to be related to the seasonality of the breed.Keywords:season; testosterone feedback; FSH; LH; breed effect; Romney; Poll Dorset; sheep

Lambs born in the autumn or winter have substantially lower birth weights than those born in the spring, but the physiological basis of this difference is unknown. This study examined the effects of season on foetal growth and placental development in ewes managed under controlled grazing to minimise the confounding effects of maternal liveweight change. Mature Romney ewes pregnant to matings in December (n = 13) or March (n - 13), with similar liveweights at mating, were managed to achieve similar liveweights at Day 140 of gestation. At that time, measures of foetal growth and placental development, adjusted for litter size, were (December- versus March-mated): foetal weight (4.15 ± 0.16 versus 5.07 ± 0.16 kg, P < 0.001); total foetal weight per ewe (6.42 ±0.18 versus 7.14 ± 0.22 kg, P < 0.01); caruncle number (114.5 ± 4.1 versus 121.0 ± 4.2, P > 0.10); placentome number (89.4 ± 4.2 versus 106.9 ± 4.3, P < 0.01); number of placentomes per number of caruncles (0.79 + 0.03 versus 0.88 ± 0.03, P < 0.05); and total placentome weight (564.7 + 34.0 versus 679.0 ± 34.9 g, P < 0.05). Maternal circulating concentrations of prolactin, IGF-1, and growth hormone are reported. This study has demonstrated that the marked seasonal differences in foetal growth are associated with seasonal differences in placental size, the formation of placentomes being significantly reduced in December-mated ewes.

Patterns of change in the weights of organs (brain, liver, kidney, heart, lungs, thymus, and thyroid) and some muscles and bones of the hind leg were assessed using 106 lamb foetuses distributed evenly over the foetal age range from 69 to 146 days. Differences between five genotypes (Merino, Romney, Merino x Romney, Drysdale, and Wiltshire), two sexes (male and female), and two pregnancy rank categories (single and multiple) for foetal growth indicated that Merino foetuses grew more slowly than all other genotypes (P < 0.01) and that females were lighter than males (P < 0.001). Crown-rump lengths at a foetal weight of 3 kg were lower for the Romney and Drysdale genotypes (P < 0.05) and for males relative to females. There were several significant genotype effects on organ weights but these did not appear to form a consistent pattern. Thus the Romney had the lightest brain, the Merino the lightest liver but the heaviest brain and lungs, and the Drysdale had the lightest thyroid and thymus. Femur and tibia weights at a foetal weight of 3 kg were greatest for the Merino and for females, but the weights of muscles around the femur differed little between genotypes or sexes. Allometric growth ratios for the weights of organs (except the heart), bones, and muscles decreased with increasing foetal weight. When adjusted to a constant bone weight, both the femur and tibia were longest for the Merino group and females. Leg muscle to bone ratio was lower for females, but did not differ between genotypes. Leg muscularity in contrast, was lower for the Merino group than for any of the others, and was also lower for females. It is concluded that appreciable genotype differences exist in patterns of foetal growth.

The effects of lambing policy (June- or August-lambing) and ewe breed cross on midside patch wool growth and wool quality traits were studied for 12 months. Three ewe crosses—Border Leicester × Romney (BR), Poll Dorset × BR (PBR), and Suffolk × BR (SBR)—were used. Twenty ewes of each cross within each lambing policy and balanced for litter size had midside patches clipped at approximately 6-weekly intervals for 1 year from April. Annual ewe fleece production was measured at the October shearings preceding and following the trial. June-lambing ewes produced 0.6 and 0.4 kg more greasy and clean wool respectively than August-lambing ewes (P < 0.001). This extra wool production was not paralleled by a greater total wool growth from midside patches in June-lambing ewes throughout the 392-day measurement period. There was, however, a difference in the pattern of wool growth between the two groups. The seasonal decline in wool production that normally occurs over the winter months in August-lambing ewes was reduced in June-lambing ewes. Associated with the extra winter wool production in June-lambing ewes was a significant increase in mean fibre diameter (P < 0.05) and staple strength (P < 0.001) when measured at the following October shearing. Wool from the June-lambing ewes was brighter and whiter (P < 0.05) than that from August-lambing ewes. There was no difference in wool bulk or resilience between the two policies. Of the ewe crosses investigated, the BR had the highest greasy wool production (4.4 ± 0.1, 3.4 ± 0.1, 3.0 ± 0.1 kg for BR, PBR, and SBR respectively, P < 0.001), mean fibre diameter (P < 0.05), and wool tensile strength (P < 0.001). The SBR had the lowest wool production, mean fibre diameter, and wool tensile strength but the highest wool bulk. The practical implications of the increased winter wool production in June-lambing ewes are discussed.

The growth, reproduction, carcass and meat quality characteristics of once-bred Hereford × Friesian (H × F) and Simmental × Friesian (S × F) heifers mated to Angus sires and managed for high gain ("HG” group) or low gain ("LG” group) during mid pregnancy (i.e. pregnancy days 114-214 = P114-P214) were compared in this study. Liveweights at mating of S × F heifers (347 ± 6 kg) were slightly higher (P < 0.10) than those of H × F heifers (333 ± 5 kg). From P114 until P214, HG heifers had significantly higher (P < 0.001) growth rates (0.72 ± 0.03 kg/day) than the LG group (0.16 ± 0.02 kg/day). This resulted in a higher liveweight in HG heifers at P214 (P < 0.001) and P270 (P < 0.01) than in the LG heifers. Gestation length, calving score, and liveweight loss at calving were not influenced by dam genotype or mid-pregnancy liveweight gain. Liveweight gain of the 24 heifers that suckled calves was not affected by dam genotype or prior liveweight gain of the dam during the suckling period or from weaning to slaughter (an average liveweight gain of 0.33 kg/day). Calf birth weight, weaning weight, and daily liveweight gain during a 106-day suckling period were not influenced by genotype or prior liveweight gain of the dam. Final heifer liveweight was slightly lower (P < 0.10) in LG versus HG heifers (476.4 versus 512.7, PSE = 16.2 kg). Dressing-out percentage was significantly (P < 0.05) higher in H × F heifers than in the S × F group, while mid-pregnancy liveweight gain had no effect on dressing-out percentages. There was a tendency (P < 0.10) for H × F versus S × F or HG versus LG heifers to produce carcasses with greater levels of fat. However, muscularity and meat quality traits were not affected by dam genotype or mid-pregnancy liveweight gain. Results are discussed in the context of beef production from once-bred S × F versus H × F heifers under New Zealand conditions.

Twenty 14-month-old Friesian steers and sixteen 14-month-old Angus cross steers were randomly assigned within “breed” to Compudose® treatment (24 mg of oestradiol-17β impregnated in a silicone rubber implant with an active life of 200 days) or left untreated. Fasted liveweight gain (LWG) of the steers was recorded as were calculated herbage intakes and grazing behaviour, measured on two occasions (days 34-50 and days 168-184 of treatment). Compudose-treated steers gained a mean of 856 g/day compared with 710 g/day by the control steers over the treatment period (20.6% increase, P < 0.001). The final fasted liveweight of treated steers was improved by 29.5 kg (7.1%) over that of the untreated steers (P < 0.001). There were no significant differences in the amount of herbage eaten or in components of grazing behaviour between the treated and untreated groups. Under pastoral conditions, as in feedlots, Compudose treatment appears to increase both LWG and the efficiency of that gain.

Although insulin-like growth factor-binding protein-2 (IGFBP-2) is an abundant IGFBP in fetal and postnatal plasma, its regulation is not yet clearly understood. To address this question in sheep, we purified ovine IGFBP-2 and developed a homologous radioimmunoassay. We have studied its ontogenesis and measured serum concentrations of ovine IGFBP-2 after bovine growth hormone (bGH), ovine placental lactogen (oPL) and IGF-I treatment.Concentrations of IGFBP-2 were high at 125 days of gestation (550 ± 15 μg/l) but fell after birth P<0·05) and plateaued after 1 year of age (340 ± 20 μg/l). In lactating ewes, bGH treatment for 7 days significantly reduced (21%; P<0·05) IGFBP-2 relative to the saline-treated group. Similarly, in neonatal lambs, bGH treatment from day 3 to day 23 of life reduced (P<0·05) IGFBP-2 by 23% relative to the saline-treated group. oPL had no effect on serum levels of IGFBP-2 in the ewe or the neonatal lamb. In well-fed yearling lambs, treatment with IGF-I reduced IGFBP-2 values by 27% (P<0·05) relative to control animals. In yearling lambs, reduced nutrition increased plasma IGFBP-2 (41%; P<0·05). However this increase was abolished by IGF-I treatment.The changes in plasma levels of IGFBP-2 were positively related to changes in IGF-II while there was a negative relationship between circulating IGF-I and IGFBP-2 such that both IGF-I and IGF-II may play a role in the regulation of IGFBP-2 in serum.Journal of Endocrinology(1995) 144,75–82

The role of insulin-like growth factor I in the regulation of fetal growth was investigated in two lines of mice selected for high or low concentrations of this factor in plasma. In Expt 1, females from each line were mated with males of the reciprocal line to generate fetuses of equivalent genotype. Females with low concentration of the factor in plasma exhibited the typical negative relationship between mean fetal mass and litter size (b= −0.032 ± 0.006 g per fetus, P< 0.01). However, dams of the line with high concentrations of the factor did not exhibit this relationship (b= −0.004 ± 0.006 g per fetus), despite the fact that they had 26% larger litters (P< 0.05) at a common maternal body mass. This difference in maternal constraint apparently reflects a greater capacity for nutrient transfer to the fetuses in the dams with more insulin-like growth factor I in plasma, as suggested by the absence of a relationship between mean placental mass and mean fetal mass in that line. In Expt 2, the effect of fetal genotype for insulin-like growth factor I was investigated by transferring embryos of the two lines into females of an unrelated strain. Fetuses from the line with high concentrations of the factor in plasma were heavier at term (1.51 versus 1.37 g, pooled se= 0.05 g, P< 0.05) than fetuses from the line with low concentrations in plasma. It is therefore concluded that fetal growth is influenced by both the maternal and fetal genotypes for insulin-like growth factor I, but in qualitatively different manners.

Summary.Reproductive performance, mammary gland weight and plasma concentrations of insulin-like growth factor-1 (IGF-1) were examined in 18-day-pregnant mice from lines divergently selected on the basis of plasma IGF-1 concentration. Females of the high IGF-1 (H) line were 14% heavier than those of the low IGF-1 (L) line at mating but did not differ in conception rate during a 15-day mating period. H-line females produced significantly larger litters by an average of 1 ·5 fetuses (19%), heavier fetuses (7%), greater total fetal weight (30%), heavier placental discs (15%), greater total placental weight (35%) and heavier mammary glands (18%). Plasma IGF-1 values were 12% greater in H-line than L-line females at Day 19 of gestation but the line difference was not significant. It is concluded that differences between the lines in litter size and mammary gland weight are most likely due to differences in maternal bodyweight (which are in turn a consequence of selection for plasma IGF-1 at puberty). Whether the difference in fetal weight is a function of fetal capacity to grow in uteroor ability of the dam to provide nutrients for fetal growth is yet to be determined.Keywords:insulin-like growth factor-1; conception; litter size; fetus; mammary gland; mouse

Follows the trip of a 70-foot Magnum yacht through the Panama Canal to its new home in San Diego, Calif. Mechanical problems encountered; What is required of a boat using the Panama Canal; Description of the Canal leg of the trip.

Recounts a 1,500 mile run from Miami to Panama aboard a Magnum 70 motorboat. Modifications made for long-distance cruising; Problems with officials; Bad weather; Mechanical difficulties.

Examines five stylish sportboats from 20 to 31 feet that are great fun for summer days. Wellcraft 202; Maxum 2300; Rinker 260; Four Winns 285; Sea Ray 310.

Examines the three best boats for billfishing. Phoenix 27 Tournament; Ocean 53 Super Sport; Black Watch 36 Open.

Examines the Tiara 270, one of the best of the new sportboats from S2 yacht. Performance; Engine combinations; Cabin; Advantages as a party boat.

Examines three new boats for the serious fisherman. Grady-White 28; Luhrs 29; Phoenix 33; Description of the boats; Their performance.

Examines the Tempest 42 Sport Yacht an innovative and fast cruising performance boat. Description of cabin; Drive system; Cockpit; Exhaust system.

Reports on the new Emergency Position Indicating Radio Beacons which eliminate the guesswork in search and rescue operations. How they work; Problems with the existing EPIRB scheme; Price; Description.

The objective was to examine myogenesis in two situations expected to be characterized by maternal constraint: (i) in fetuses due to be born in spring (n = 10) or autumn (n = 10); and (ii) in single (n = 16) and twin (n = 20) fetal lambs. Maternal constraint operating through limitation of placental size, as measured by placentome weight per fetus, was evident in each study. Although a lower placental weight did not inßuence body and muscle weights of fetuses due to be born in the spring or autumn, twins had lower body and muscle weights than singles. Fibre number and average bre cross-sectional (CS) area were differentially affected by season and fetal number. The differences in muscle bre morphology between spring- and autumn-born fetuses suggest that muscle bre development was inßuenced by maternal constraint in the absence of an effect on fetal weight. The differences in muscle bre number and CS area in particular muscles from twin and single fetuses suggest that more severe maternal constraint, reßected in a lower placental size per fetus, not only inßuences fetal weight but can also affect muscle development. Extra keywords: season, rank, fetus, sheep.

This study investigated the effects of Compudose® on growth, lactational performance, carcass characteristics, and offspring performance of Hereford × Friesian (H×F) once-bred heifers (OBH) under pastoral conditions. Nineteen H×F heifers were implanted with Compudose 400 at 90 days of age (Compudose 90), 19 were implanted with Compudose 400 at 210 days of age (Compudose 210), and 19 were not implanted (control). Neither Compudose group differed significantly in liveweight from the controls. However, there was a tendency for the Compudose 90 group to be slightly heavier, and the Compudose 210 group slightly lighter, than the controls so that the only significant differences in liveweight were between the two Compudose groups. Similarly, there were no consistent effects of Compudose on measures of body or skeletal size. The effects of Compudose on carcass characteristics were small and related mainly to a tendency for increased muscling. Compudose delayed conception slightly but had no effects on calf birthweight. However, calves born to control heifers were 15·3 kg and 16·2 kg heavier (P &lt; 0·05) at weaning than calves born to Compudose 90 and Compudose 210 heifers, respectively. Most of this difference in liveweight was established by Week 4 of lactation. This implies that Compudose treatment inhibited milk production of the dams, particularly in the early part of lactation, an effect not detected by the weigh-nurse-weigh (WNW) method. Implanting heifers with Compudose at 90 or 210 days of age is unlikely to be beneficial, both because it has little positive effect on liveweight gain or carcass characteristics and because it may inhibit lactational performance. Additional keywords: breeding heifers, liveweight gain, pastoral conditions.